Styrenic foam laminates have been used as acoustical and thermal insulation for a variety of applications, for instance as automobile headliners. Recent advances in this area have lead to the development of thermoformable styrenic foam laminates which can be provided in complex shapes. Such laminates are able to retain a desired shape because of the use of deformation-resistant coatings, for instance a polymer-impregnated fabric facing on at least one surface of the styrenic foam components. For illustrative laminates see U.S. patent applications Ser. Nos. 553,594 filed Nov. 17, 1983 and now U.S. Pat. No. 4,476,183; 553,462 filed Nov. 17, 1983 and now U.S. Pat. No. 4,489,126; 647,095, filed Sept. 4, 1984 and now U.S. Pat. No. 4,526,829; 647,096 filed Sept. 4, 1984 and now U.S. Pat. No. 4,531,994; 647,311 filed Sept. 4, 1984 and now U.S. Pat. No. 4,557,970; and 648,547 filed Sept. 7, 1984 and now U.S. Pat. No. 4,529,641 all of which are incorporated herein by reference.
To thermoform such laminates to useful shapes for acoustical and thermal insulation applications, the laminates are preheated to thermoforming temperatures of the styrenic foam components prior to thermoforming. Such preheating is generally effected as rapidly as possible, for instance by infrared radiation heaters, which may bring the surface temperatures of the laminates to temperatures as high as about 177.degree. F. or higher. After such laminates are thermoformed into shapes for acoustical or thermal insulation applications, it is often desirable to provide a decorative trim to the exposed surface of the shaped laminate. For instance, when such thermoformed laminates are used for automobile headliners, a decorative trim, such as polyurethane foam covered with a decorative fabric or vinyl facing, is generally utilized for an enhanced aesthetic appearance. Because such layer of polyurethane foam faced with decorative fabric provides thermal insulation which would increase the time for preheating the styrenic foam thermoforming temperatures, decorative layers are applied to the laminate structures after thermoforming to the desired shape. Consideration of overcoming the adverse increase in heating time by applying heat from hotter sources, e.g. infrared radiation heaters, have been dismissed as impractical because the resulting higher surface temperatures would be expected to degrade the decorative trim e.g. often faced with nylon fabric.
I also believe that attempts have been made to thermoform thermosetting, phenolic resin-impregnated layers of fiberglass batting having decorative trim of urethane foam faced with fabric. I understand that such attempts have been unsuccessful because at thermoforming temperatures the uncured phenolic resin flows through the decorative trim resulting in stained and hardened trim.
An object of this invention is to provide a method for thermoforming styrenic foam laminates having an outer layer of decorative trim of urethane foam faced with a fabric.
A further object of this invention is to provide a method for such thermoforming which is free from undue delays in heating and thermoforming processes and which did not adversely affect the aesthetic appearance of the decorative trim.
These and other objects of this invention will be apparent from the following description and claims.